Insulin and insulin-like growth factor (IGF-I) receptors in the brain are similar in structure to their non-neural peripheral counterparts. However, they have smaller apparent molecular weights and differ in the glycosylation of their subunits. In addition, the role of insulin and IGF-I in neuronal cells differ when compared to other cells. To investigate the mechanisms for these differences we have begun studies that include structure and function studies of the insulin and IGF-I receptors in brain. To this end we have cloned and sequenced the rat IGF-I receptor cDNA and its proximal promoter. These tools will allow us to study regulation of gene expression of this receptor. In addition, since early metabolic actions of these hormones include glucose uptake, we have also investigated the gene expression of the brain-type glucose transporter (glut 1) in neuronal and glial cells in culture.